Computing

Generator (category theory)

In category theory in mathematics a family of generators (or family of separators) of a category is a collection of objects, indexed by some set I, such that for any two morphisms in , if then there is some i∈I and morphism , such that the compositions . If the family consists of a single object G, we say it is a generator (or separator).

Generator (circuit theory)

A generator in electrical circuit theory is one of two ideal elements: an ideal voltage source, or an ideal current source. These are two of the fundamental elements in circuit theory. Real electrical generators are most commonly modelled as a non-ideal source consisting of a combination of an ideal source and a resistor. Voltage generators are modelled as an ideal voltage source in series with a resistor. Current generators are modelled as an ideal current source in parallel with a resistor. The resistor is referred to as the internal resistance of the source. Real world equipment may not perfectly follow these models, especially at extremes of loading (both high and low) but for most purposes they suffice.

The two models of non-ideal generators are interchangeable, either can be used for any given generator. Thévenin's theorem allows a non-ideal current source model to be converted to a non-ideal voltage source model and Norton's theorem allows a non-ideal voltage source model to be converted to a non-ideal current source model. Both models are equally valid, but the voltage source model is more applicable to when the internal resistance is low (that is, much lower than the load impedance) and the current source model is more applicable when the internal resistance is high (compared to the load).

Park West, Dublin

Park West (Irish:Páirc an Iarthair) is a large business campus within greater Ballyfermot, notably Cherry Orchard, Dublin, Ireland, with some residential development.

There are over 300 companies with 10,000 employees.

Location and content

Located just inside the M50 orbital motorway in west Dublin, the development comprises several million square metres of office and retail space, along with an Aspect hotel, a private hospital, and three apartment complexes.

Art

Park West is home to Europe's tallest wind and water mobile sculpture, Wave by Angela Conner. It is a 39.3 metre (129 feet) tall sculpture made of polystyrene covered with layers of carbon resin. It is fixed into a 7.6 metre (25 foot) pit filed with 9.5 tonnes of lead.

Wave (Antonio Carlos Jobim album)

Wave is the third album by Antônio Carlos Jobim, released in 1967 on A&M Records. It is known as Jobim's most successful album to date (# 5 US JAZZ ALBUMS 1967,# 114 US ALBUMS 1968), and it was listed by Rolling Stone Brazil as one of the 100 best Brazilian albums in history.

Wave (audience)

The wave (known as the Mexican wave in the anglosphere outside North America) is an example of metachronal rhythm achieved in a packed stadium when successive groups of spectators briefly stand, yell, and raise their arms. Immediately upon stretching to full height, the spectator returns to the usual seated position.

The result is a wave of standing spectators that travels through the crowd, even though individual spectators never move away from their seats. In many large arenas the crowd is seated in a contiguous circuit all the way around the sport field, and so the wave is able to travel continuously around the arena; in discontiguous seating arrangements, the wave can instead reflect back and forth through the crowd. When the gap in seating is narrow, the wave can sometimes pass through it. Usually only one wave crest will be present at any given time in an arena, although simultaneous, counter-rotating waves have been produced.

Origins and variations

1970s–1980s

While there is general disagreement about the precise origin of the wave, most stories of the phenomenon's origin suggest that the wave first started appearing at North American sporting events during the late 1970s and early 1980s. Krazy George Henderson led a wave in October 15, 1981 at a Major League Baseball game in Oakland, California. This wave was broadcast on TV, and George has used a videotape of the event to bolster his claim as the inventor of the wave. On October 31, 1981, a wave was created at a UWfootball game in Seattle, and the cheer continued to appear during the rest of that year's football season. Although the people who created the first wave in Seattle have acknowledged Krazy George's wave at a baseball stadium, they claimed to have popularized the phenomenon, since Krazy George's wave was a one-time event.